Wow, stomatopods have always fascinated me... a friend of mine did an internship at the Smithsonian, where she sorted squid beaks from whale stomachs, and generally among the beaks she would find the remains of one (never more than one) mantis shrimp... we used to speculate on whether the whale learned its lesson after that one, or whether it was an accidental ingestion that turned out to be its last.
What are you keeping it in, and what will you feed it?

right now it is in a 20g tank with a good amount of sand and rock, i didnt go all out with the a bigger tank cuz this thing is probably full grown and not going to live long, i read they grow between 8 to 10 inches, thats about this things size.

the lady at the store said they were feeding it shrimp so thats what im going to try, i just got it today